The electrocardiographic signal (ECG), is an electrophysiological signal that contains information essentially related to the cardiac activity, but it is also modulated by the respiratory activity. Therefore, one of the signals that can be obtained from the ECG is known as ECG-derived respiratory signal (EDR). ECG and respiratory flow signal from 45 elderly patients have been analysed. The EDR signal was obtained by identifying the R wave in the QRS complex from the ECG, and applying a fourth-order statistical processing method. The method generates a discrete value for every heartbeat, and all together they contain the modulation of the respiratory signal. By interpolation and filtering this signal, an estimation of the instantaneous respiratory volume was obtained. The results were validated using the MGH/MF database from PhysioNet. The EDR signal was correlated with the respiratory volume from the Elderly database. According to the results, the EDR signal can be a good estimation of the respiratory activity, and could allow to identify different respiratory patterns in elderly patients.